Biaxial Nematic Phase in Model Bent-Core Systems

We determine the bifurcation phase diagrams with isotropic (I), uniaxial (N-U) and biaxial (N-B) nematic phases for model bent-core mesogens using Onsager-type theory. The molecules comprise two or three Gay-Berne interacting ellipsoids of uniaxial and biaxial shape and a transverse central dipole. The Landau point is found to turn into an I-N-B line for the three-center model with a large dipole moment. For the biaxial ellipsoids, a line of Landau points is observed even in the absence of the dipoles.